This invention relates to a method of bonding a diamond compact to a cemented carbide substrate.
Diamond compacts consist of a polycrystalline mass of diamond produced under diamond synthesis conditions. Diamond compacts have a high diamond content, for example, higher than 80 percent by volume, and generally contain a second or bonding phase. An example of a second or bonding phase is one which contains silicon, with or without a diamond catalyst/solvent. The silicon will be present largely as silicon carbide, although some residual elemental silicon will also be present.
Diamond compacts are brittle and are generally bonded to a substrate, particularly a cemented carbide substrate, for cutting and other similar operations. Bonding of silicon-containing diamond compacts to substrates presents problems. Where a braze is used for the bonding, the strengh of the braze joint can be reduced by impurities which diffuse from either the substrate or the compact into the braze layer. More particularly, for siliconcontaining compacts, even minute quantities of residual, unreacted freesilicon from the binder phase reacts preferentially with the braze producing a highly inconsistent and weakened braze joint between the compact and the substrate.